We are currently doing a pilot of the effectiveness of beta carotene or placebo on blood beta carotene levels and other biochemical markers and the possible side effects of such treatment among 400 high risk cigarette smoking men. This study has been ongoing for about two years and has clearly documented that 15 mg of beta carotene per day will substantially increase the blood beta carotene levels, over a ten-fold increase in most of the men, as compared to placebo, that adherence to the intervention is excellent and side effects are minimal. The study was designed as a Phase I pilot study to determine the feasibility of a full-scale trial of bet carotene as compared to placebo among high risk men in the prevention of lung cancer. The results of the Phase I pilot study to date have clearly documented that recruitment and successful treatment with beta carotene is feasible even among these high risk men at least in the short-term. There are no on-going studies at the present time that have either the sample size and power on the high risk population to test the efficacy of beta carotene versus placebo in the prevention of lung cancer. Several Phase I studies similar to the present are currently underway. Clinical and epidemiological and animal laboratory studies clearly documented that beta carotene has some chemopreventive activity especially against squamous cell carcinomas. It would be very important to determine whether any markers of early lung neoplasis can be identified and whether beta carotene can either modify their frequency or progression. We propose to utilize these men in a Phase I pilot study to determine whether quantitative DNA analysis of sputum epithelial cells can be used as a marker of possible pre-malignant abnormalities, and to compare it with standard sputum cytology. The study will combine the expertise of the Epidemiology Nutrition Program and the Pittsburgh Cancer Institute evolving program in lung cancer research.